1. Field of Invention
This invention relates to long-acting preparations which have actions of both rapid-release and sustained-release in spite of their single unit dosage form, and also to the process of manufacturing said preparations. In the manufacturing process of this invention, neither organic solvents nor water are used. Therefore, there is no danger of explosion. Nor is there any problem of residual solvent. Also it does not require a drying process. Thus, this process makes it possible to manufacture said sustained-release preparations easily and at a low cost.
2. Prior Art
Some methods have been reported concerning the technique of making sustained-release by effectively controlling the dissolution of water-soluble active ingredient with the use of melted fats. Such technique is divided into two main types: one is a method of making sustained-release by forming a matrix or by making a solid dispersion and the other is that of making a membrane, reservoir type preparation by coating the fats.
The method disclosed in KOKOKU No. 63-24978 belongs to the latter and attains sustained-release extending over a period of 8 hours or longer by coating an emulsion of fats in water onto the active ingredient. However, this method has a drawback in that since a W/O type emulsion of fat is spray-coated on the granules prepared beforehand, (a) it involves processes of making granules and of drying the granules, (b) it also involves further processes of drying after spray coating, etc., and (c) it requires the use of a surfactant in making an emulsion, by which a problem in safety is caused.